3 replies to this topic

[chemart]

How do i make Math.Cos to use degrees instead of radians?

if angle is 90° :

cos(90)=0 << with degrees... this one is correct

90°/57.2957795 = 1.5708 radians

Math.Cos(90) = -0.44807361612917 wrong
Math.Cos(1.5708) = -3.58659263231679E-10 wrong

[Freedom Doc]

chemart said:

How do i make Math.Cos to use degrees instead of radians?

if angle is 90° :

cos(90)=0 << with degrees... this one is correct

90°/57.2957795 = 1.5708 radians

Math.Cos(90) = -0.44807361612917 wrong
Math.Cos(1.5708) = -3.58659263231679E-10 wrong

All computer languages that do trig do so with radian measure for the angles. You just need a simple formula to convert degrees to radians first. If you have x in degrees, then pi * x / 180 will be the right value for Math.Cos() (I forget if C# has a known constant for pi but 3.14159265358979 will do just fine).

By the way, the reason Math.Cos(1.5708) is not exactly zero is due to floating point roundoff problems + the fact that 1.5708 is not exactly pi / 2. Do not expect exact answers from a system that tries to represent infinitely many real numbers with only a finite number of items -- not gonna happen.

[yulin11]

Yes ,i think you should convert the number you need.then use it in the math.cos.

codeuu

[jireh]

just have the right logic and do the tricks...